AQA AS Level Biology Revision Questions What are the three ways a pathogen can damage hosts cells?(Ans- 1) rupturing them to release nutrients inside them 2) breaking down nutrients inside the cell for their own use. This starves and eventually kills the cell.3) replicating inside the cells and bursting them when they're released What are the two ways pathogens cause disease?(Ans- 1) production of toxins 2) cell damage What are the lifestyle factors that can affect your chances of getting cancer?(Ans- 1) smoking 2) excessive exposure to sunlight 3) excessive alcohol intake What are the three surfaces of contact- where pathogens enter our body? and how do they get in?(Ans- 1) gas-exchange system = if you breathe in air that contains pathogens, most of them will be trapped in mucus lining the lung epithelium. Some pathogens are able to reach the alveoli where they can invade cells and cause damage. 1 / 2
2) Skin = if you damage your skin, pathogens on the surface can enter your bloodstream. blood clots prevent pathogens from entering.3) Digestive system = if you eat or drink food that contains pathogens. Some will survive from the acidic conditions of the stomach, and invade cells of the gut wall and cause disease.Explain the process of phagocytosis.(Ans- 1) A phagocyte recognises the antigens on a pathogene 2) The cytoplasm of the phagocyte moves round the pathogen, engulfing it.3) The pathogen is now contained in a vacuole or a vesicle in the cytoplasm of the phagocyte.4) A lysosome fuses with the phagocytic vacuole and the lytic enzymes break down with the pathogen 5) The phagocyte presents the pathogens antigens, it sticks the antigens on its surface to activate other immune system cells.What is the cellular and humoral response?(Ans- Cellular = The T-cells and other immune system cells that they interact with e.g phagocytes , form the cellular response Humoral - B cells and the production of antibodies form the humoral response.
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